JP5113549B2 - Manufacturing method of mold - Google Patents

Description

The present invention relates to a mold for manufacturing how.

  In the die casting mold, the mold that forms the molding surface of the molding cavity is injected from the injection device of the die casting machine in order to constantly stabilize the mold temperature and maintain the quality of the molding material in the production cycle. The circulating structure of the cooling water that reduces the amount of heat applied by the molten metal (Al or the like) is formed. The mainstream is called spot cooling.

  In the spot cooling, the cooling water is configured to circulate through the cooling water flow path formed in the nest. In die casting molds for automobile transmission cases, etc., a cooling water pipe with a two-layer pipe structure that mainly forms a bottomed cooling water circulation hole in the nest and forms a cooling water forward path and a return path is introduced into the cooling water circulation hole. In general, the cooling water is circulated in the order of the forward path, the cooling water circulation hole, and the return path.

  As a method of connecting the cooling water pipe and the insert, a deep hole is directly carved on the back of the insert made of tool steel, and this deep hole is used as a cooling water circulation hole, and cooling water from the cooling water pipe is used as a deep hole. A direct cooling system for direct contact and a bushing made of copper (for example, free-cutting brass such as C3601) having a deep hole as a cooling water circulation hole in the insert is press-fitted, and a cooling water pipe is inserted into the deep hole formed in this bush There is an indirect cooling system that circulates cooling water.

  In the case of the direct cooling method, since the cooling water directly touches the nesting material (mainly tool steel such as hot tool steel SKD-61), the heat conduction efficiency for cooling water (and hence the cooling efficiency by cooling water) is high. In addition, stress corrosion cracking due to hydrogen embrittlement tends to occur inside the cooling water circulation hole. For this reason, the durability tends to be low, and in some cases, the cracks reach the cavity surface of the nest and the cooling water overflows to the cavity surface.

On the other hand, in the indirect cooling method, since the cooling water circulates in the bush made of a metal material that hardly causes corrosion, such as free-cutting brass, corrosion cracking unlike the direct cooling method is less likely to occur. As a method for manufacturing an indirect cooling type insert, as disclosed in Patent Document 1, a pipe having a flow path for introducing cooling water is formed of a copper material or the like, and this pipe is a member that becomes an insert. A method is known in which a material is sandwiched between and bonded by a pressure bonding method.
JP 61-88942 A

  As described above, in the cooling structure in which the cooling water circulation hole having the bottom is provided in the nest and the cooling water is circulated in the cooling water circulation hole, it is difficult to apply a sufficient load to the hollow bush formed in the sleeve shape. Therefore, there is a problem that the pressure bonding method as in Patent Document 1 cannot be used as it is. It is also conceivable that the insert is formed of divided members and the bushing is sandwiched in the radial direction and diffusion-bonded. In that case, the bush is carried between the divided inserts, The process of sandwiching and assembling the bush is complicated, and if the insert is divided, the processing accuracy of the molding surface also deteriorates, making it difficult to form a high-precision molding cavity. Could not be avoided.

  On the other hand, when the bush is inserted into the insert without depending on diffusion bonding, there is a problem that a gap is easily generated between the bush and the insert. In particular, since the bush material is generally a soft metal material, no matter how the processing accuracy of each bush is increased, a gap is formed, and the amount of heat conducted from the insert to the cooling water is directly cooled. Compared to the method, it is greatly reduced. Even if a thermal joint (a paste made of metal) is applied to the gap for the cooling effect of cooling water, the nest and the bush cannot be brought into close contact, so the gap can be completely eliminated. There wasn't. Therefore, it has a cooling capacity equivalent to that of the direct cooling system and is difficult to maintain.

  The present invention has been made in view of the above problems, is easy to process, and has a method for producing a molding die that can produce a highly durable insert that exhibits an excellent cooling effect over a long period of time. The object is to provide a molding die.

In order to solve the above problems, the present invention comprises a mold material formed of a first metal and having a molding surface of a molding cavity, and a second metal excellent in corrosion resistance, and constitutes a cooling water flow path. A manufacturing method of a molding die that integrates a bush having a cooling water circulation hole to manufacture a molding die, and the inner back side tapers at a portion of the die material that should constitute the cooling water flow path. A taper hole forming step of forming a taper hole, and a tapered outer peripheral surface corresponding to the surface of the peripheral surface of the formed taper hole, and the tapered solid bar is formed as the second metal. A solid rod forming step formed by: a diffusion bonding step of inserting the solid rod into the tapered hole of the mold material and pressing it into the inner side of the tapered hole , and diffusion bonding them together; and diffusion Form a deep hole-shaped cooling water circulation hole in the solid rod after joining To a cooling water circulation hole forming step of forming the cooling water flow path, said first metal is steel, the second metal mold which is a copper or copper alloy It is a manufacturing method.
In this aspect, the taper hole is formed in the die material by the taper hole forming step, and the solid rod having the outer peripheral surface corresponding to the taper hole is formed by the solid rod forming step. Then, by inserting the solid bar into the tapered hole and performing diffusion bonding, the mold material and the solid bar are integrated. As defined in Japanese Industrial Standards, diffusion bonding means that “the base material (mold material and solid bar) are in close contact, and plastic deformation does not occur as much as possible under temperature conditions below the melting point of the base material. "Method of bonding by applying pressure and utilizing diffusion of atoms generated between bonding surfaces". In this diffusion bonding process, since the solid rod is inserted into the taper hole of the mold material to achieve diffusion bonding, the mold material and the solid rod can be sufficiently pressurized to form a preferable diffusion bonding site. it can. In the diffusion bonding step, an insert metal may be interposed between the mold material and the solid bar as necessary. In addition, the tapered hole has a tapered shape on the inner back side, and the outer periphery of the solid rod is formed in a tapered shape corresponding to the surface contact with the inner peripheral surface of the tapered hole. In the diffusion bonding step, the wedge-shaped solid rod is press-fitted into the tapered hole, and a dense diffusion bonding portion is formed between the mold material and the solid rod in a more preferable bonding state. Thereafter, since the cooling water flow path formed of the second metal having excellent corrosion resistance is formed by the cooling water circulation hole forming step, the manufactured mold has a high resistance to water by the cooling water flow path formed of the second metal. While having corrosiveness, it is possible to exhibit good heat conduction characteristics by a dense diffusion bonding portion with the mold material, and to exhibit a high cooling effect over a long period of time.

Furthermore, since the first metal is steel and the second metal is copper or a copper alloy, it is possible to obtain a suitable diffusion bonding portion by purifying and adhering the bonding surface with both materials. become.

  In a preferred embodiment, a molding surface forming step of forming the molding surface after the diffusion bonding step is provided. In this aspect, in the diffusion bonding process, as much load as possible can be applied to the mold material and the solid rod in the diffusion bonding process with the unground portion as the pressure-receiving surface, and the load is applied. By grinding the mold material after being formed to form a molding surface, a molding surface with high processing accuracy can be formed.

  In a preferred embodiment, a pressure receiving surface forming step of forming a pressure receiving surface at the time of diffusion bonding on the mold material prior to the diffusion bonding step is provided. In this aspect, the portion formed by the pressure-receiving surface forming process can be used as the pressure-receiving surface, and as large a load as possible can be applied to the mold material and the solid rod during the diffusion bonding process.

  In a preferred embodiment, the metal material includes a quenching process in which the metal material is heated at a predetermined heating temperature after the diffusion bonding process and then rapidly cooled, and the second metal to be the material of the solid rod is heated to the heating temperature. The metal having a higher melting point is selected, and in the diffusion bonding step, heating is performed for a predetermined time at a temperature equal to or lower than the heating temperature in the quenching step. In this aspect, diffusion bonding between the mold material and the solid bar can be achieved at as high a temperature as possible. That is, the diffusion bonding method is a technique for bonding metals using a diffusion phenomenon of metal atoms, and the diffusion phenomenon is evaluated by a diffusion coefficient D in Fick's law. The temperature dependence of the diffusion coefficient D is expressed by the following equation (1).

D = D ₀ exp (−Q / RT) (1)
However, D ₀ : Frequency factor Q: Activation energy R: Gas constant T: Temperature As is clear from the equation (1), the diffusion coefficient D has a characteristic of rapidly increasing as the temperature increases. In the diffusion bonding method, as long as other processing elements (for example, prevention of embrittlement after tempering due to coarsening of austenite particles) are satisfied, it is preferable to increase the temperature at the time of bonding as much as possible. In this respect, in this aspect, the first and second metals are materials having a melting point higher than the heating temperature in the quenching process, and in the diffusion bonding process, the heating is performed at the heating temperature in the quenching process. Diffusion is further promoted, and a desired joint structure can be obtained.

  In a preferred embodiment, the second metal is oxygen-free copper. Generally, in the indirect cooling method, a cooling water channel of free-cutting brass is formed in the insert, but since this free-cutting brass has a melting point of around 900 ° C., the temperature required for the quenching process (1000 ° C. to 1050 ° C.) This is because there is a risk of melting. On the other hand, since oxygen-free copper (C1020) has a melting point of around 1080 ° C., there is no risk of melting even in the quenching process, and in diffusion bonding, it is preferable to heat by heating to the heating temperature in the quenching process. It becomes possible to plan.

  In a preferred embodiment, the method includes an annealing step in which the mold material after the diffusion bonding step is heated at a temperature lower than the heating temperature in the quenching step before the quenching step and then gradually cooled. In this aspect, the martensitic transformation in the quenching process can be promoted more suitably. That is, in the diffusion bonding process, since considerable heat and pressure are applied and rapid cooling is difficult, the mold material has a mixed structure including martensite, residual austenite, bainite and the like. Therefore, even if the process immediately shifts to the quenching process, a high-quality martensite structure cannot be obtained, and hardness and toughness suitable as a mold cannot be obtained. On the other hand, the mold material is transformed into a spherical pearlite single phase by heating the mold material again to a predetermined temperature and gradually cooling it after the diffusion bonding step. As a result, in the subsequent quenching process, the martensitic transformation of the mold material is promoted, and it is possible to obtain a high-quality martensitic structure that can obtain suitable hardness and toughness as a mold by the subsequent tempering process. It becomes.

  As described above, in the present invention, a diffusion bonding site is formed between the mold material made of the first metal and the bush made of the second metal having excellent corrosion resistance. Remarkable that it has corrosion resistance and exhibits good heat conduction characteristics due to a dense diffusion bonding site with the mold material, is easy to process, and can exhibit a high cooling effect over a long period of time. There is an effect.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a process diagram illustrating a method for manufacturing a die casting mold insert according to an embodiment of the present invention. Moreover, FIGS. 2-5 is explanatory drawing of each process.

  First, with reference to FIG. 1 and FIG. 2 (A) (B), in embodiment shown to the figure, the metal mold | die raw material 10 and the solid stick 20 are manufactured in parallel first (process ST1-ST5). ).

  Specifically, a tapered hole forming step ST1 for forming the bottomed tapered hole 11 in the mold material 10 of the hot tool steel SKD-61 as the first metal is performed. The taper hole 11 is hollowed out by a cutting device, for example, and is formed in a taper shape in which the bottom side is narrowed. The tapered hole 11 has a parallel opening end 11a and a tapered portion 11c that partitions the shoulder portion 11b between the opening end 11a to form a tapered inner surface, and the innermost portion of the tapered portion 11c is It is finished in a spherical shape. Hereinafter, in the description of FIGS. 2 to 6, the opening end side of the tapered hole 11 is temporarily referred to as the upper side.

  After the taper hole forming step ST1, a shape roughing step ST2 for roughing the mold material 10 in a circular cross section around the axis L of the taper hole 11 is performed. The rough-cut mold material 10 has a small-diameter portion 12 formed on the upper portion (opening end 11 a side of the tapered hole 11) and a large-diameter portion 15 that forms a shoulder portion 14 together with the small-diameter portion 12. . A pressure receiving surface 16 is formed on the bottom of the mold material 10. The pressure receiving surface 16 is a surface that receives the load when the solid rod 20 press-fitted into the tapered hole 11 is pressed into the inner side of the tapered hole 11 during the diffusion bonding step ST6. In the present embodiment, this rough shape cutting step ST2 includes a pressure receiving surface forming step for forming the pressure receiving surface 16 at the time of diffusion bonding on the mold material 10 prior to the diffusion bonding step ST6.

  The mold material 10 that has undergone the shape roughing process ST2 is subjected to a cleaning process ST3 by a well-known method. In particular, the oxide film in the tapered hole 11 is removed and the surface is cleaned by the cleaning process ST3. The

  In parallel with the above-described steps ST1 to ST3, a solid rod forming step ST4 for manufacturing the solid rod 20 to be bonded to the mold material 10 by a cutting device and a cleaning step ST5 are performed.

  The solid bar 20 cut out by the solid bar forming step ST4 includes a cylindrical part 21 corresponding to the opening end 11a of the tapered hole 11, a step part 22 corresponding to the shoulder part 11b, and a taper corresponding to the taper part 11c. This is a solid metal bar having the portion 23 integrally. The stepped portion 22 and the tapered portion 23 are formed in a state where the specifications are set so as to make surface contact with the corresponding shoulder portion 11b and the tapered portion 11c. On the other hand, the cylindrical portion 21 is set to have a slightly longer dimension than the opening end 11a, and at the time of assembly, a crushing margin in which a part protrudes upward from the upper end surface 17 of the mold material 10 appears. It has been set (see FIG. 3B).

  As the material of the solid rod 20, oxygen-free copper (C1020) as the second metal is suitably employed. This is because, in the quenching step ST9 described later, the mold material 10 is heated to 1030 ° C., and thus oxygen-free copper having a melting point higher than that of a free-cutting brass, which is a general material, is adopted.

  After the solid bar 20 is manufactured, the solid bar 20 is also subjected to a cleaning process ST5 by a well-known method. By this cleaning process ST5, the oxide film on the surface of the solid bar 20 is removed, and the surface Is cleaned.

  Next, referring to FIG. 1 and FIG. 3, the cleaned mold material 10 and the solid rod 20 are formed with the tapered portion 11 of the solid rod 20 in the tapered hole 11 as shown in FIG. The diffusion bonding step ST <b> 6 is performed in a state in which the peripheral surface of the solid rod 20 is closely attached to the entire circumference of the tapered hole 11 in the vacuum furnace 30.

  FIG. 6 is a timing chart showing a specific example of the heat treatment according to the embodiment of the present invention.

  With reference to FIG. 6, in this diffusion bonding step ST <b> 6, the pressure receiving surface 16 of the mold material 10 is placed on the placement surface 31 of a not-shown press device, and the crushing portion of the solid rod 20 is pressed by the presser 32. Is pressed at a pressure of about 15 MPa, and in this state, the temperature is raised stepwise and heated to a target temperature (about 1030 ° C. in the illustrated example). After reaching the target temperature, a predetermined time t1 (for example, 1 hour), pressure And the temperature are maintained in the vacuum furnace 30 and then slowly cooled. In the present embodiment, the target temperature is set to 1030 ° C. in order to prevent the austenite particles from coarsening and embrittlement after tempering by heating the mold material 10 to an excessively high temperature. However, as is clear from the equation (1) shown in the solution section, the diffusion coefficient D has a characteristic of rapidly increasing as the temperature rises, and the temperature at the time of joining is as much as possible. In the present embodiment, diffusion bonding at a high target temperature is achieved by employing oxygen-free copper.

  In this diffusion bonding step ST6, the solid rod 20 is inserted into the taper hole 11 of the mold material 10 to achieve diffusion bonding. Therefore, the mold material 10 and the solid rod 20 are sufficiently pressurized to provide a preferable diffusion bonding. A region 41 (see FIG. 4A) can be formed. In the diffusion bonding step ST6, an insert metal may be interposed between the mold material 10 and the solid rod 20 as necessary, and solid phase diffusion bonding or liquid phase diffusion bonding may be performed. Further, the tapered hole 11 has a tapered shape on the inner back side, and is formed in a tapered shape corresponding to the outer periphery of the solid bar 20 so as to be in surface contact with the inner peripheral surface of the tapered hole 11. Therefore, in the diffusion bonding step ST6, the wedge-shaped solid rod 20 is press-fitted into the tapered hole 11, and a dense diffusion bonding portion between the mold material 10 and the solid rod 20 in a more preferable bonding state. 41 is formed.

  Referring to FIG. 1 and FIG. 4, the die material 10 and the solid rod 20 that have finished the diffusion bonding step ST <b> 6 are inserted into a die casting die as a molding die having a diffusion bonding portion 41 at the bonding portion between them. The child 40 is configured.

  The die casting mold insert 40 is taken out from the vacuum furnace 30 and subjected to a rough shape cutting step ST7 by a cutting device, whereby a cavity molding surface 42 is formed in the lower part of the mold material 10. In the present embodiment, since the shape roughing step ST7 is performed after the diffusion bonding step ST6, the pressure receiving surface 16 shown in FIGS. 2 and 3 is formed, and the diffusion bonding step ST6 has a more suitable posture. The mold material 10 and the solid bar 20 can be pressurized. As described above, in this embodiment, the rough shape cutting step ST7 includes a molding surface forming step of forming the molding surface 42 after the diffusion bonding step ST6.

  As shown in FIG. 1 and FIG. 4 (B), the die-cast mold insert 40 on which the cavity molding surface 42 is formed is subjected to heat treatment in the heating furnace 50 (steps ST8 to ST10).

  Next, referring to FIG. 6, as described above, in the diffusion bonding step ST6, the heating temperature is gradually increased, and after reaching the target temperature, the pressure and temperature are maintained for a predetermined time t1 to perform diffusion. It is performed by causing bonding and then slowly cooling. The mold material 10 at the point A when the diffusion bonding step ST6 is finished has a mixed structure including martensite, pearlite, retained austenite, bainite and the like. Therefore, even if the process immediately shifts to the quenching process, a high-quality martensite structure cannot be obtained, and hardness and toughness suitable as a mold cannot be obtained. Therefore, in the present embodiment, the annealing step ST8 is performed prior to the quenching step ST9.

  In the annealing step ST8, the die casting mold insert 40 is heated in the heating furnace 50, and the temperature is raised to a predetermined target temperature (for example, 850 ° C.). Then, after maintaining the heating temperature for a predetermined time t2 (for example, 1 hour), it is gradually cooled. The structure of the mold material 10 at the time B when the annealing step ST8 is completed is transformed into a single phase of spherical pearlite. As a result, in the subsequent quenching step ST9, the martensitic transformation of the mold material is promoted, and a good quality martensite structure capable of obtaining hardness and toughness suitable as a mold can be obtained by the subsequent tempering step ST10. It becomes possible.

  A quenching step ST9 is performed after the annealing step ST8.

  In the quenching step ST9, holding times t3 and t4 are provided for each predetermined temperature, and the die casting mold insert 40 is heated so that the temperature is raised as evenly as possible. For example, in the present embodiment, the first holding time t3 is provided between 450 ° C. and 650 ° C., and the second holding time t4 is provided between 700 ° C. and 850 ° C. Each holding time t3, t4 is set to about 1 hour.

  In the quenching process ST9, the spherical pearlite single-phase structure is heated to a heating temperature (1030 ° C. in the illustrated example) sufficient to transform it into a martensite structure (may have some retained austenite). When this heating temperature is reached, the heating furnace 50 is thereafter controlled to maintain the heating temperature constant for a predetermined time t5 (for example, about 1 hour). Thereafter, the die casting mold insert 40 is rapidly cooled by a method such as gas cooling, water cooling, or oil cooling. In this rapid cooling time t6, the temperature is controlled so as to cool to 510 ° C. within 30 minutes, for example.

  The structure of the mold material 10 at the time C when the quenching process ST9 is completed is a structure of martensite and retained austenite.

  The martensite structure at this stage is hard but has a low yield point and is in a fragile state. Therefore, in the present embodiment, in order to obtain a martensitic structure having high toughness, the tempering step ST10 is performed at a relatively high temperature (for example, 550 ° C.).

  In this tempering step ST10, the die-casting mold insert 40 is heated to a target temperature (for example, 550 ° C.) and then gradually cooled (cooled).

  The structure of the die material 10 at the time point D when the tempering step ST10 is completed is transformed into a tempered martensite having high toughness.

  Next, with reference to FIG. 1 and FIG. 5, the die-casting die insert 40 that has finished the tempering step ST10 is processed again by the grinding device. First, the upper end surface 17 of the mold material 10 and the upper surface 43 of the solid bar 20 are ground to be flush with each other by the planar processing step ST11 (see FIG. 5A). Thereafter, a bottomed cooling water circulation hole (deep hole) 44 is formed along the axis of the solid rod 20 by the cooling water circulation hole forming step ST12 (see FIG. 5B). The cooling water circulation hole 44 is formed with a fitting portion 44a on the inlet side into which a cooling water pipe 109, which will be described later in detail, is fitted, and a diameter smaller than the fitting portion 44a, and a shoulder portion 44b is defined between the fitting portion 44a. It has concentrically with a circulating part 44c on the bottom side for circulating the cooling water. The fitting portion 44a and the circulation portion 44c of the cooling water circulation hole 44 are both straight cylinders. By forming the cooling water circulation hole 44, the solid rod 20 constitutes a bush in the present invention. In addition, at the time of execution of cooling water circulation hole formation process ST12, the joining quality of the diffusion interface (diffusion joining part) 41 formed between the metal mold | die material 10 and the solid rod 20 is determined by the presence or absence of isolation | separation by a processing load, etc. Is also possible.

  Next, the outer peripheral surface of the die casting die insert 40 is finished by the shape finishing step ST13. Finally, a dimension inspection is performed to complete the die casting die insert 40.

  Next, a description will be given of the die casting apparatus 100 that employs the die casting die insert 40 manufactured through the above-described steps ST1 to ST13.

  FIG. 7 is a schematic cross-sectional view of the die casting apparatus 100 according to the embodiment of the present invention. In the following description, the left side of FIG.

  With reference to FIG. 7, a die casting apparatus 100 according to the present embodiment includes a fixed platen 101 and a movable platen 102 disposed in front of the fixed platen 101.

  Between the fixed platen 101 and the movable platen 102, a fixed matrix 103 fixed to the front surface of the fixed platen 101 is disposed. Between the fixed matrix 103 and the movable platen 102, the movable matrix 104 is arranged. Is arranged. The movable mother die 104 is integrated with the movable platen 102 by a die base 105 disposed on the front surface thereof, and is configured to be movable back and forth with the movable platen 102 at a predetermined interval in the front-rear direction.

  Between the fixed mother mold 103 and the movable mother mold 104, a fixed insert 106 fixed to the front surface of the fixed mother mold 103 and a movable insert 107 fixed to the rear surface of the movable mother mold 104 are arranged. Thus, an annular cavity 108 is formed facing each other in the front-rear direction. The die insert die insert 40 formed through the manufacturing procedure described above is fixed to the fixed insert 106. A cooling water pipe 109 extending in the front-rear direction passes through the fixed mold 103, and a front end portion of the cooling water pipe 109 is introduced into the cooling water circulation hole 44 of the die casting mold insert 40.

  FIG. 8 is an enlarged view of a main part of FIG.

  Referring to FIG. 8, a cooling water pipe 109 includes an inner pipe 109a that constitutes an outward path of the cooling water, and an outer pipe 109b that is arranged concentrically with a gap constituting a return path of the cooling water around the inner pipe 109a. have. The outer pipe 109b is press-fitted into a fitting portion 44a that constitutes the cooling water circulation hole 44 of the die casting insert 40 through a seal (not shown). Further, the inner pipe 109 a is introduced to the inner depth side of the cooling water circulation hole 44 with respect to the outer pipe 109 b and opens near the bottom of the circulation portion 44 c of the cooling water circulation hole 44. A nozzle portion 109c is formed at the upstream end of the outer pipe 109b. A supply port 109d that communicates with the upstream end of the inner pipe 109a to supply cooling water to the nozzle portion 109c, the outer periphery of the inner pipe 109a, and the outer pipe 109b. A discharge port 109e is formed in communication with the inner periphery to discharge the cooling water that has returned from the cooling water circulation hole 44. Then, the cooling water supplied from the supply port 109d to the inner pipe 109a flows into the cooling water circulation hole 44 to cool the die casting mold insert 40, and then between the inner periphery of the outer pipe 109b and the outer periphery of the inner pipe 109a. The cooling water is moved back and discharged from the discharge port 109e.

  Referring to FIG. 7, movable mold 104 is provided with a diverter 110 that forms a part of the outer peripheral portion of cavity 108 and a slide core 111. Among these, the slide core 111 is fixed to the slide core holder 113 so as to be displaceable relative to the movable insert 107, and is driven via the slide core holder 113 by the core cylinder 112 fixed to the movable matrix 104. It is configured to be.

  On the other hand, the fixed mother die 103 is provided with a casting port bush 114 that communicates with a part of the cavity 108 so as to face the back surface of the current divider 110 fixed to the movable mother die 104. An injection sleeve 115 is continuous on the upstream side (rear side) of the casting port bush 114. The injection sleeve 115 is formed with an introduction port 115a for introducing aluminum 116 as a molten metal to be a molding material, and the aluminum 116 introduced from the introduction port 115a is transferred from the front casting port bush 114 to the cavity 108. A plunger tip 118 of a plunger rod 117 to be pushed in is provided slidably. The injection sleeve 115, the plunger rod 117, etc. constitute the injection device in this embodiment.

  Further, in order to take out a molded product molded in the cavity 108, the movable platen 102 is provided with an extrusion rod 120, and an extrusion plate 121 is fixed to the rear end portion thereof. An extrusion pin 122 is fixed to the extrusion plate 121 in a cantilevered manner, passes through the rear movable mother die 104 and the movable insert 107 and faces the cavity 108.

  When the workpiece is molded by the die casting apparatus 100 shown in FIG. 7, the movable platen 102 and the movable insert 107 are driven as shown in FIG. A cavity 108 is formed between the fixed insert 106 and the die casting mold insert 40. In parallel with this, the slide cylinder 111 is held in the state shown in the figure by the core cylinder 112 via the slide core holder 113. In this state, aluminum 116 as a raw material is introduced from the introduction port 115a of the injection sleeve 115, and the aluminum 116 introduced by the plunger tip 118 of the plunger rod 117 is pushed into the cavity 108 from the front casting port bush 114 to be solidified. Mold in a predetermined time until completion.

  During this molding, cooling water is supplied to the cooling water pipe 109, and the die casting insert 40 is cooled.

  In more detail with reference to FIG. 8, the cooling water supplied from a cooling water supply circuit (not shown) passes through the inner pipe 109a from the supply port 109d of the cooling water pipe 109, and enters the insert 40 for the die casting mold. It is introduced into the cooling water circulation hole 44 and absorbs the heat of the die casting die insert 40. Then, it flows through the flow path formed in the cooling water circulation hole 44, flows to the inner peripheral side of the outer pipe 109b, returns to the rear, and is discharged from the discharge port 109e.

  In the present embodiment, when the cooling water circulation hole 44 is formed, the solid rod 20 is diffusion bonded into the taper hole 11 of the mold material 10, and then the cooling water circulation hole 44 is formed by grinding. The copper material and the mold material 10 are joined at a dense diffusion joining portion 41. As a result, it is possible to maintain high resistance to thermal stress over a long period of time, and to prevent generation of cracks.

  A die casting molding apparatus 100 shown in FIG. 7 embodies a die casting type of a transmission case provided in an automatic transmission. In the experiment conducted by the present inventors, even after 30000 shots were cast, no leakage of cooling water occurred, and no rust was generated in the die casting mold insert 40. Also in the cooling capacity, the mold temperature, which is a good condition of the shape material, can be maintained, and a high level is maintained in both quality and operation rate.

  As described above, in the present embodiment, the cooling water flow path forming step ST12 forms a cooling water flow path formed of a metal (oxygen-free copper) having excellent corrosion resistance. No. 40 has high corrosion resistance due to the oxygen-free copper cooling water flow path, and exhibits good heat conduction characteristics due to the dense diffusion bonding portion 41 with the mold material 10, and exhibits a high cooling effect over a long period of time. It becomes possible.

  In the present embodiment, a rough shape forming step ST7 is provided as a molding surface forming step for forming the cavity molding surface 42 after the diffusion bonding step ST6. For this reason, in the present embodiment, in the diffusion bonding step ST6, an unground portion is used as the pressure receiving surface 16, and as much load as possible is applied to the mold material 10 and the solid rod 20 in the diffusion bonding step ST6. In addition, the cavity molding surface 42 having high processing accuracy can be formed by grinding the mold material 10 after the load is applied to form the cavity molding surface 42.

  Further, in the present embodiment, prior to the diffusion bonding step ST6, a rough shape cutting step ST2 as a pressure receiving surface forming step for forming the pressure receiving surface 16 at the time of diffusion bonding on the mold material 10 is provided. For this reason, in this embodiment, it can give to the metal mold | die material 10 and the solid stick | rod 20 by receiving as large load as possible in the pressure bonding surface 16 in the case of diffusion joining process ST6.

  In the present embodiment, the first metal is tool steel, and the second metal is oxygen-free copper. For this reason, in this embodiment, it becomes possible to clean and bond the joint surfaces with both materials, and to obtain a suitable diffusion bonding portion 41.

  Further, in the present embodiment, the mold material 10 is provided with a quenching step ST9 in which the mold material 10 is heated at a predetermined heating temperature (1030 ° C.) after the diffusion bonding step ST6 and then rapidly cooled, and becomes the material of the solid rod 20 The metal is made oxygen-free copper having a melting point higher than the heating temperature (1030 ° C.) in the quenching process ST9, and in the diffusion bonding process ST6, it is heated for a predetermined time at a temperature equal to or lower than the heating temperature in the quenching process ST9. is there. For this reason, in the present embodiment, diffusion bonding between the mold material 10 and the solid rod 20 can be achieved at as high a temperature as possible. That is, the first and second metals are materials having a melting point higher than the heating temperature in the quenching step ST9, and in the diffusion bonding step ST6, the first metal and the second metal are heated at the heating temperature in the quenching step ST9. It is possible to promote and obtain a desired joint structure.

  In the present embodiment, the second metal is oxygen-free copper. In general, in the indirect cooling method, a cooling water channel of free-cutting brass is formed in the insert, but since this free-cutting brass has a melting point of around 900 ° C., the temperature required for the quenching step ST9 (1000 ° C. to 1050 ° C. ) Is likely to melt. On the other hand, oxygen-free copper (C1020) has a melting point of around 1080 ° C., so there is no risk of melting even in the quenching step ST9, and in diffusion bonding, it is preferable to warm to the heating temperature in the quenching step ST9. Diffusion bonding can be achieved.

  In the present embodiment, the mold material 10 after the diffusion bonding step ST6 is heated at a temperature lower than the heating temperature in the quenching step ST9 before the quenching step ST9, and then annealed in the annealing step ST8. I have. For this reason, in this embodiment, the martensitic transformation in quenching process ST9 can be accelerated | stimulated more suitably. That is, in the diffusion bonding step ST6, a considerable amount of heat and pressure are applied, and rapid cooling is difficult. Therefore, the mold material 10 has a mixed structure including martensite, pearlite, residual austenite, bainite, and the like. It has become. Therefore, even if it transfers to hardening process ST9 immediately, a quality martensite structure cannot be obtained and hardness and toughness suitable as a metal mold cannot be obtained. On the other hand, the mold material 10 is transformed into a spherical pearlite single phase by heating the mold material 10 again to a predetermined temperature and gradually cooling it after the diffusion bonding step ST6. As a result, in the subsequent quenching process ST9, martensitic transformation of the mold material 10 is promoted, and a good martensite structure capable of obtaining hardness and toughness suitable as a mold is obtained by the subsequent tempering process ST10. Is possible.

  The above-described embodiment is merely a preferred specific example of the present invention, and the present invention is not limited to the above-described embodiment.

  For example, the present invention can be applied not only to die casting of aluminum as described above but also to a resin molding die.

  It goes without saying that various modifications can be made within the scope of the claims of the present invention.

It is process drawing which shows the manufacturing method of the molding die concerning embodiment of this invention. It is explanatory drawing of each process in the manufacturing method of the molding die concerning embodiment of this invention, (A) is sectional drawing of a mold raw material, (B) is a side view of a solid stick. It is sectional drawing of the metal mold | die raw material of the diffusion joining process in the manufacturing method of the metal mold | die which concerns on embodiment of this invention. It is sectional drawing of the metal mold | die raw material of the diffusion joining process in the manufacturing method of the metal mold | die which concerns on embodiment of this invention. It is sectional drawing of the metal mold | die raw material of the diffusion joining process in the manufacturing method of the metal mold | die which concerns on embodiment of this invention. It is a timing chart which shows the specific example of the heat processing which concerns on embodiment of this invention. 1 is a schematic sectional view of a die casting apparatus according to an embodiment of the present invention. It is a principal part enlarged view of FIG.

10 Mold material 11 Tapered hole 16 Pressure-receiving surface 20 Solid rod (Bush material)
40 Die-cast mold insert (example of mold)
41 Diffusion bonding part 42 Cavity molding surface 44 Cooling water circulation hole 100 Die casting molding apparatus 108 Cavity 109 Cooling water pipe 116 Aluminum (an example of molten metal)
ST1 Tapered hole forming process ST2 Shape roughing process (an example of pressure receiving surface forming process)
ST3 Cleaning process ST4 Solid rod forming process ST5 Cleaning process ST6 Diffusion bonding process ST7 Shape roughing process (an example of molding surface forming process)
ST8 Annealing process ST9 Quenching process ST10 Tempering process ST11 Planing process ST12 Cooling water circulation hole forming process ST13 Shape finishing process

Claims (6)

A mold material that is formed of the first metal and has a molding surface of the molding cavity and a bush that is formed of a second metal that is excellent in corrosion resistance and that has a cooling water circulation hole that constitutes the cooling water flow path are integrated. A manufacturing method of a molding die for manufacturing a molding die,
A taper hole forming step for forming a taper hole in which the inner back side tapers in a portion that should constitute the cooling water flow path of the mold material,
A solid rod forming step of forming a tapered solid rod with the second metal, and having a tapered outer circumferential surface corresponding to the circumferential surface of the formed tapered hole;
A diffusion bonding step of inserting the solid rod into the tapered hole of the mold material and pressing it into the inner side of the tapered hole to diffusely bond both;
A cooling water circulation hole forming step of forming a cooling water circulation hole by forming a deep hole cooling water circulation hole in a solid rod after diffusion bonding ,
The method for producing a molding die, wherein the first metal is steel, and the second metal is copper or a copper alloy . In the manufacturing method of the shaping die according to claim 1,
The manufacturing method of the molding die characterized by including the molding surface formation process which forms the said molding surface after the said diffusion bonding process. In the manufacturing method of the shaping die according to claim 2,
Prior to the diffusion bonding step, a pressure receiving surface forming step for forming a pressure receiving surface at the time of diffusion bonding on the mold material is provided. In the manufacturing method of the shaping die according to any one of claims 1 to 3 ,
The metal material is provided with a quenching step of heating at a predetermined heating temperature after the diffusion bonding step and then rapidly cooling,
The second metal to be a material of the solid rod is selected from metals having a melting point higher than the heating temperature, and the diffusion bonding step is heated for a predetermined time at a temperature equal to or lower than the heating temperature at the quenching step. A method for producing a molding die, characterized in that In the manufacturing method of the shaping die according to claim 4 ,
Said 2nd metal is an oxygen free copper. The manufacturing method of the shaping die characterized by the above-mentioned. In the manufacturing method of the molding die according to claim 4 or 5 ,
A mold material after the diffusion bonding step is provided with an annealing step of gradually cooling after heating at a temperature lower than the heating temperature in the quenching step before the quenching step. Mold manufacturing method.

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